haskell - fmap (+1) $ read "[1]" gives error -


when type repl fmap (+1) $ read "[1]" expect [2] instead error :

no instance (functor f0) arising use of ‘it’

unfortunately doesn't me. explain me wrong snipped of code.

it doesn't know type read value into. specifying type explicitly:

fmap (+1) $ (read "[1]" :: [int])

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